The present invention relates to the field of attenuators for laser radiation or radiation from collimated light sources.
Present methods of attenuating radiation utilize materials which are absorbent to radiation from a beam impinging thereon. This approach presents a problem because the absorbent materials are prone to heat damage and variability in their properties with respect to thermal distortions. The materials also deviate the attenuated beam from the direction of the incident beam. A further disadvantage of this approach is that a particular material does not attenuate radiation over large ranges of frequency. Thus, a substitution of materials is required when the frequency of the incident radiation is changed. Lastly, in order to vary the amount of attenuation provided one must alter the amount of material placed in the direction of the incident beam, thereby introducing an additional phase shift.